Use a comma to join two independent clauses and a coordinating conjunction (and, but, or, for, nor, so).
- Road construction can be inconvenient, but it is necessary.
- The new house has a large fenced backyard, so I am sure our dog will enjoy it.
- To get a good grade, you must complete all your assignments.
- Because Dad caught the chickenpox, we canceled our vacation.
- After the wedding, the guests attended the reception.
- On her vacation, Lisa visited Greece, Spain, and Italy.
- In their speeches, many of the candidates promised to help protect the environment, bring about world peace, and end world hunger.
Use a comma to separate nonessential elements from a sentence. More specifically, when a sentence includes information that is not crucial to the message or intent of the sentence, enclose it in or separate it by commas.
- John’s truck, a red Chevrolet, needs new tires.
- When he realized he had overslept, Matt rushed to his car and hurried to work.
Use a comma between coordinate adjectives (adjectives that are equal and reversible).
- The irritable, fidgety crowd waited impatiently for the rally speeches to begin.
- The sturdy, compact suitcase made a perfect gift.
Use a comma after a transitional element (however, therefore, nonetheless, also, otherwise, finally, instead, thus, of course, above all, for example, in other words, as a result, on the other hand, in conclusion, in addition)
- For example, the Red Sox, Yankees, and Indians are popular baseball teams.
- If you really want to get a good grade this semester, however, you must complete all assignments, attend class, and study your notes.
Use a comma with quoted words.
- “Yes,” she promised. Todd replied, saying, “I will be back this afternoon.”
Use a comma in a date.
- October 25, 1999
- Monday, October 25, 1999
- 25 October 1999
Use a comma in a number.
- 1614 High Street
Use a comma in a personal title.
- Pam Smith, MD
- Mike Rose, Chief Financial Officer for Operations, reported the quarter’s earnings.
Use a comma to separate a city name from the state.
- West Lafayette, Indiana
- Dallas, Texas